Pre-pologies if this is an old question. I did my best to search. I've got a large part I'd like to eventually cast in rubber/silicone.

Because it's so big, I'm thinking of the following technique:

1.)Print master "positive" in sandstone (for economic reasons)

2.)Create mold of positive using traditional RTV molding techniques

3.)Cast part in silicone.

I fully expected destruction of the sandstone master upon de-molding which would be fine, assuming the mold is successful. I'm imagining a pretty much total disintegration at that point...just so long as it holds up until the mold cures!

My question here is mostly whether anyone would caution against sandstone as a "positive" material for reasons other than its fragility.

Texture-wise, I'm actually hoping for a somewhat rough surface in the casting, so to me sandstone offers that built in

Any advice? Thanks in advance,

Jared

P.S. I'm also hoping to take advantage of the 15% off deal ending tonight, so fast answers will be much appreciated.

I know some artists who actually did this with FSC, although in their case they sanded and painted the positive first (it was for a bronze casting and required a smooth finish). They actually re-used the original afterwards, so if you're careful enough it may survive!